What happens to Babbitt material as it begins to cool?

When Babbitt material begins to cool, it undergoes a transformation that can lead to changes in its structural integrity. As it cools, Babbitt can indeed become brittle, which is an important consideration in its application for bearings. The brittleness can affect the performance of the bearing, particularly under stress or load, hence careful selection and handling during installation are crucial.

In the context of this material's behavior, cooling can lead to internal stresses and microstructural changes that contribute to brittleness. Therefore, recognizing this characteristic is vital for those working with Babbitt bearings, as it impacts their longevity and functionality in machinery.

Evaluating the other options provides additional clarity on why they do not represent the phenomenon correctly. Rapid expansion typically occurs in materials during heating rather than cooling, while solidification without shape change is not accurate since cooling Babbitt involves specific structural modifications. The idea of separation into multiple layers does not apply to the cooling process of Babbitt, as this material is designed to maintain homogeneity during solidification.